Exploration of metabolic responses towards hypoxia mimetic DMOG in cancer cells by using untargeted metabolomics

Abstract

Hypoxia is considered as one of the most crucial elements of tumor microenvironment. The hypoxia inducible transcription factors (HIF-1/2) are used by the cancer cells to adapt hypoxic microenvironment through regulating the expression of various target genes, including metabolic enzymes. Dimethyloxalylglycine (DMOG), a hypoxic mimetic used for HIF stabilisation in cell and animal models, also demonstrates multiple metabolic effects. In past, it was shown that in cancer cells, DMOG treatment alters mitochondrial ATP production, glycolysis, respiration etc. However, a global landscape of metabolic level alteration in cancer cells during DMOG treatment is still not established. In the current work, the metabolic landscape of cancer cells during DMOG treatment is explored by using untargeted metabolomics approach. Results showed that DMOG treatment primarily alters the one carbon and lipid metabolism. The levels of one-carbon metabolism related metabolites like serine, ornithine, and homomethionine levels significantly altered during DMOG treatment. Further, DMOG treatment reduces the global fatty acyls like palmitic acids, stearic acids, and arachidonic acid levels in cancer cell lines. Additionally, we found an alteration in glycolytic metabolites known to be regulated by hypoxia in cancer cell lines. Collectively, the results provided novel insights into the metabolic impact of DMOG on cancer cells and showed that the use of DMOG to induce hypoxia yields similar metabolic features relative to physiological hypoxia.

Keywords: Dimethyloxalylglycine (DMOG); Fatty acyls; Hypoxia; Lipidomics; Untargeted Metabolomics.

Fig. 1

Metabolomic analysis of cancer cells treated with DMOG. (A) Pathway analysis of overlapping upregulated genes from RNA-seq of physiological hypoxia and DMOG induced hypoxia (B) Total ion chromatogram of cell treated cells with DMOG (C) PCA analysis of total metabolites of HeLa and HCT116 cancer cells.

Fig. 2

(A-B). Heat map of differentially modulated metabolites between DMOG treated and control using Ward based clustering.

Fig. 3

Top pathways and metabolite enrichment analysis in DMOG treated cancer cells. (A) Metabolic pathway enriched in DMOG treated HeLa and HCT116 cells versus control; (B) Variable important for projection (VIP) scores of top 15 important metabolite features identified in DMOG treated cancer cells.

Fig. 4

DMOG alter crucial energy metabolic pathways in cancer cells. Quantitative peak intensities of various metabolites involved in TCA cycle in DMOG treated HeLa and HCT116 cells versus control, * p < 0.01. ** p < 0.00.

Fig. 5

DMOG alter one carbon metabolism of cancer cells. Quantitative levels of various metabolites involved in methionine pathway of control and DMOG treated cells, * p < 0.01. ** p < 0.00.

Fig. 6

DMOG alter lipid metabolism in cancer cells. (A) lipids involved in metabolic pathway. (B) Major structural class of lipids were mapped using MetaboAnalyst (C) Main structural class of lipids were mapped using MetaboAnalyst (D) The total accumulation of lipid in major structural class (E) The total accumulation of lipid in main structural class and their quantitative levels.

Fig. 7

DMOG alters fatty acid and prenol lipid class of cancer cells. Quantitative levels of various lipid class and their classification in control and DMOG treated cells, * p < 0.01. ** p < 0.00.